As living standards improve, people pay more and more attention to interior as well as exterior decoration of windows, doors and outer walls of amongst other buildings and vehicles. Society furthermore demands for new decorative and safe glass applications.
Single as well as multi-layered glass can be decorated. Multi-layering of glass sheets therewith provides an enhanced mechanical stability of the glass. Multi-layered glass sheets also allow to include decorative features between the different glass layers.
There is significant commercial interest in the fabrication of customized multi-layered glass panels with encapsulated coloured decoration for use in architectural and automotive applications.
Because of its ceramic nature, glass however is a very challenging substrate for decorating, coating and printing. Adhesion of inks to glass is very difficult because of the low contact area. In addition, many glass applications (such as in construction) require a very robust solution.
Standard organic or semi-organic inks printed on glass are not sufficiently durable for many glass applications.
One known approach to printing on glass is printing with ceramics. Since a post baking step is required in this approach to harden the inks and adhere them to the glass, disadvantages are the investment in baking equipment, extra process time and high energy costs. Further disadvantages are the investment cost in a dedicated ceramics printer and lower resolution than standard inkjet printers.
Printing of silane-containing inks is technically difficult because there are problems with blockage of print heads. This requires an intensive flushing increasing the ink cost. This furthermore requires a post heat treatment leading to investments in ovens increasing the energy costs and factory area.
In the patent literature, already several methods and approaches for manufacturing multi-layered decorative panels or decorated laminated safety glass panels have been described, circumventing or trying to solve the difficulties as described above to decorate glass.
It is commonly known to apply decorated foils between glass plates and other types of substrates. It is furthermore commonly known to apply adhesive films between glass plates and other types of substrates. Well known examples of such adhesive films are polyvinyl butyral sheet or ethylene vinyl acetate sheets.
In EP 2 030 778 for instance, a decorative laminated glass is described comprising two transparent substrates and an intermediate film including two adhesive resin films and a base film having an ink layer printed in a predetermining pattern therebetween. The intermediate film is arranged between the transparent substrates to be combined with each other.
In US 2004/0234735, a method and apparatus is described for producing an image carrying laminated material. An image is printed on a polyvinylbutyral interlayer using a solvent based ink, paint or dye system. The interlayer is used to join two sheets of material to form the laminate.
In DE 3232238, a pane of laminated glass is made of two individual panes of glass and a thermoplastic intermediate layer, the latter joined to one another A particularly decorative effect is given due to the fact that one individual pane of glass is printed with narrow stripes, arranged parallel to one another, of a printable ink on the surface joined to the thermoplastic intermediate layer.
In US 2008/0105371, a process is described for preparing a decorative glass laminate comprising a rigid thermoplastic interlayer, wherein the process comprises printing an image onto at least one of the interlayer surfaces.
In WO 2005/085371 and WO 2006/050536, the decorative laminated article comprises an image bearing thermoplastic interlayer, wherein the image has been printed on the interlayer using an inkjet printing process. The image therewith comprises a white pigment on the surface of the thermoplastic interlayer.
In EP 1 651 434, a decorative glass laminate is disclosed comprising a rigid interlayer bearing a printed image that has been printed onto at least one of the interlayer surfaces. Also a process for preparing the same is disclosed.
In DE 20 2010 002 822, a glass laminate, in particular for doors, windows, roof covers, etc. is disclosed. Therein, a top side and a lower surface of the glass laminate are formed by a windowpane. Between the upper-lateral windowpane and the under-lateral windowpane, at least partially a printable foil layer out of foil plastic is arranged. Furthermore, at least between the printable foil layer and the upper-lateral windowpane and/or between the printable foil layer and the under-lateral windowpane, a connecting foil out of a connecting plastic is arranged.
In US 2008/0206504, an image-bearing article is described comprising a rigid sheet bearing an image which is coated on the image-bearing side and over the image with an adhesion promotor. The image-bearing side of the rigid sheet can be laminated to a polymeric interlayer sheet such as a polyvinyl butyral (PVB) or ethylene vinyl acetate (EVA) sheet. To this interlayer sheet, a second rigid sheet can be laminated.
In US 2007/0172636, a decorated polymer sheet is disclosed. At least one of the surfaces of this sheet has disposed thereon an image which is applied to the sheet by a digital printing process. Furthermore, at least this surface has disposed therein an adhesive composition that is used to enhance the bond strength between the image disposed on the polymer sheet and other materials, particularly to another layer in a laminate structure. At least a portion of this adhesive composition is therewith in contact with the image. This decorated polymer sheet can be incorporated in a laminate having at least one additional layer. This additional layer will generally and preferably be in contact with a surface of the decorated polymer sheet upon which the image and the adhesive composition are disposed.
In JP 2011190133, a decorative laminated glass is disclosed in which at least two glass plates are laminated with a resin interlayer film. At least one of the glass plates carries a pattern layer inkjet-printed with an ultraviolet-curable resin ink. A primer layer is provided between the pattern layer and the glass plate. An adhesive layer consisting of a polyvinyl acetal resin or a polyvinyl butyral resin is provided between the pattern layer and the resin interlayer film.
In EP 2 030 778, a decorative laminated glass is disclosed comprising two transparent substrates and an intermediate film including two adhesive resin films and a base film having an ink layer printed in a predetermining pattern therebetween. The intermediate film is arranged between the transparent substrates to be combined with each other. The base film is subjected to an adhesion-facilitating treatment. The adhesive film comprises an ethylene vinyl acetate copolymer.
The disadvantage of printing of foil and lamination using adhesive films requires a large investment in pressing and heating (autoclave) equipment and low-dust environment.
The disadvantage of PVB adhesive films is that PVB is moisture sensitive.
EVA adhesive films have the disadvantage that these are difficult to handle because of sticking/tackiness. EVA usually contains 33% of vinyl acetate; this being a very soft and tacky substance that tends to stick to itself. This tackiness makes handling of the EVA-material in a manufacturing environment much more troublesome.
A further disadvantage is that foil lamination of tempered glass with a print is difficult since foil lamination requires very flat glass and tempered can have a curvature of several millimeters.
Other lamination solutions using coatings require a complex and time-consuming process (drying and heat treatment).
There is consequently a desire to obtain a multi-layered decorative panel                having a high quality;        being safe;        without the need of a complex production process, for instance without the need of an additional baking treatment, i.e. on high temperatures above 100° C.;        without the need of additional solvent-based coatings that consume time to dry;        without the need of large investments in equipment or a (dust and moisture) controlled environment;        without the need of a large factory area for printing and lamination processes; and        having the possibility to apply many types of (digitally printed) rigid panels.        